Evolved Packet Core (EPC) is the Internet Protocol (IP)-based core network defined by the 3rd generation partnership project (3GPP) in Release-8 for use by long-term evolution (LTE) and other access technologies. The goal of EPC is to provide a simplified all-IP core network architecture to efficiently provide access to various services, such as the ones provided in IMS (IP Multimedia Subsystem). The 3GPP Evolved Packet Core provides a means by which a wireless communication/mobile device (referred to as User Equipment (UE) in 3GPP parlance) is able to access a Packet Data Network (PDN). The only means by which a UE can access a PDN in the present standard is by means of a PDN gateway (GW). This requires that traffic traverse the entire Evolved Packet Core (EPC) before reaching the PDN GW. An EPC consists essentially of a Mobility Management Entity (MME) and access-agnostic Gateways for routing of user IP datagrams. Currently a UE accesses a PDN by means of the EPC network (sometimes referred to as core network), via the PDN GW and an SGi interface.
Selective IP Traffic offload (SIPTO) is a known mechanism that provides a means by which a radio access node (for example an eNodeB (eNB) or a Home Node B or a Home eNodeB (H(e)NB)) is able to directly exchange IP data with external PDNs. FIG. 1 illustrates a first known mechanism 100 using SIPTO. Here, a UE 105 exchanges IP data with an external PDN 135 via EPC. The exchange of IP data 130 is made through an eNB or H(e)NB 120 and a server-gateway (S-GW) or PDN GW 125. The exchange of IP data 115 is switched from the eNB or H(e)NB 120 through a Gateway General Packet Radio System (GPRS) Support Node (GGSN) or PDN GW 110 coupled to the eNB or H(e)NB 120. The IP data is then directly exchanged with the external PDN 135.
FIG. 2 illustrates a second known mechanism 200 using SIPTO. Here, a UE 205 again exchanges IP data with an external PDN 235 via EPC. The exchange of IP data 230 is again made through a eNB or H(e)NB 220 and a server-gateway (S-GW) or PDN GW 225. Again, in contrast to the IP data exchange via EPC, the network may decide to use a direct SIPTO connection. Here, the exchange of IP data 215 is transferred through the eNB or H(e)NB 220 and a notational address translation (NAT) module and layer-3 router 210 coupled to the eNB or H(e)NB 220. The IP data is then directly exchanged with the external PDN 235.
Thus, in order to use SIPTO, the UE has needed to create an additional, dedicated PDN connection, in order to activate a switch to the SIPTO connection (termed a SIPTO ‘breakout’). Hence, in essence, the UE must initiate the break out. Furthermore, there is no chance of mobility for connections from the SIPTO to any non-SIPTO access, or vice versa, unless Mobile IP is enabled on top of the 3GPP links (which is currently prohibited in Rel.9 of the 3GPP standard development). Finally, the SIPTO-breakout has to occur on demand, i.e. the UE must know that the correct conditions exist in order for SIPTO to be used and, thus, a stimulus needs to be received by the UE in order to enable the breakout to a use of a SIPTO PDN connection.
Despite the numerous above-mentioned limitations, such direct exchange of data between the UE and a PDN server using a SIPTO connection provides several benefits. For example, the direct exchange of data using SIPTO allows the Network Operator to be able to offload excess data traffic. In addition, in some cases, better performance for the end user may be achieved, for example in a Home network or an Enterprise network situation when the network that the end user connects to is physically close to the end user, or even attached to the radio access node. In some cases, SIPTO may also provide access to networks that otherwise cannot be reached, especially home networks (for example a Home eNodeB offering access to a home WLAN).